Calponin is an actin filament-associated regulatory protein. H2-calponin is a member of the calponin family that includes two other homologous isoforms, h1-calponin and acidic calponin. The extensively studied h1-calponin is specific to differentiated smooth muscle cells. H2-calponin is found in smooth muscle and a number of non-muscle cells with a potentially broad physiological function. As an interesting example, endothelial cells express a substantial level of h2-calponin, implicating a functional significance for this protein not necessarily shared by its homologous isoforms. Endothelial cell proliferation and migration are critical for proper vascular development and wound healing. Over-expression of h2-calponin inhibits cell proliferation.